The earliest my quick grep could find was 4.0BSD. I didn't find it in this
sense in pwb, but it was a quick grep...

xxx is used extensively in prior versions, but there it's meaning is
'placeholder' or 'don't care'. Mostly for /tmp/XXXX files, but also for
things like Jxxx handles all the jump commands or dates of the form 24 Feb
XXXX or stuff like that.

Warner

On Thu, Sep 3, 2020 at 11:34 AM Dave Horsfall <dave@horsfall.org> wrote:

> For yonks I've been seeing "XXX" as a flag to mean "needs more work" or
> "look at this carefully, just in case" etc, and I use it myself.
>
> Whence did it come about?  I think I saw it as early as PWB, but can't be
> sure.
>
> -- Dave, wondering how many nanny-filters he triggered with "XXX"
>